After opening of trading, currency in difficulty (7)
I believe the answer is:
trouble
'difficulty' is the definition.
(I know that difficulty can be written as trouble)
'after opening of trading currency' is the wordplay.
'after' means one lot of letters go next to another.
'opening of' indicates taking the first letters.
'currency' becomes 'rouble' (Russian rouble).
The initial letter of 'trading' is 't'.
't'+'rouble' is 'TROUBLE'.
'in' is the link.
(Other definitions for trouble that I've seen before include "Strife, difficulty" , "Distress, upset or worry" , "Jam" , "'A... shared is a... halved'" , "Trial, care, worry" .)